A method and an apparatus to which the invention relates are described in U.S. Pat. No. 4,672,934. A provisional desired air quantity which is to result in a specific desired speed is determined as a function of values of various operating parameters, especially the engine temperature, gear position or switching state of an air-conditioning system. In order to guarantee that this desired speed is actually obtained, the control deviation between the desired speed and actual speed is used to form a value for a regulating air quantity which is added to the value of the provisional desired air quantity in order to obtain the actual desired air quantity. From this desired air quantity, a control value, especially a pulse-duty factor, is calculated for the idling adjuster by means of an air quantity control-value characteristic stored in a memory. When the characteristic is determined correctly, the idling adjuster is controlled by means of the read-out control value exactly in such a way that the actual intake air quantity precisely corresponds to the desired air quantity required. In contrast, if the characteristic is incorrect, for example because of a change in density of the air since the last determination of the characteristic or a change in the leakage-air fraction, an air quantity control deviation between the desired air quantity and actual air quantity is obtained. An adaptation of the mentioned characteristic is carried out by means of this air-quantity control deviation.
Accordingly, the known apparatus for adapting the characteristic curve of an idling adjuster has a speed subtraction means for forming the speed control deviation, an air-quantity subtraction means for forming the air-quantity control deviation, a characteristic memory and an adaptation means. Furthermore, a release means for releasing the adaptation is provided. The adaptation of the slope of the characteristic is released, for example, when a predetermined air-quantity throughput is exceeded. Offset adaptation takes place, for example, whenever the slope adaptation does not occur and a blocking time has elapsed.
When this apparatus and therefore the associated method are used, it has emerged that often less quiet running is obtained after a starting operation then without this apparatus and without this method.
On the one hand, it is the object of the invention to provide a method for adapting the characteristic curve of an idling adjuster by means of which smooth engine running can be achieved quickly, even after a starting phase. On the other hand, it is the object of the invention to provide an apparatus for carrying out such a method.